Dislocation damping in metals

Short-period cyclic loading system for in situ X-ray observation of anelastic properties at high pressure

To determine the anelastic properties of materials of the Earth's interior, a short-period cyclic loading system was installed for in situ X-ray radiographic observation under high pressure to the multi-anvil deformation DIA press at the bending magnet beam line BL04B1 at SPring-8. The hydraulic system equipped with a piston controlled by a solenoid was designed so as to enable producing smooth sinusoidal stress in a wide range of oscillation period from 0.2 to 100 s and generating variable amplitudes. Time resolved X-ray radiography imaging of the sample and reference material provides their strain as a function of time during cyclic loading. A synchrotron X-ray radiation source allows us to resolve their strain variation with time even at the short period (<1 s). The minimum resolved strain is as small as 10^-4, and the shortest oscillation period to detect small strain is 0.5 s. Preliminary experimental results exhibited that the new system can resolve attenuation factor Q^-1 at upper mantle conditions. These results are in quantitative agreement with previously reported data obtained at lower pressures.